Super strong adhesive is created

DAYTON, Ohio, Oct. 16 (UPI) -- U.S. scientists say they've created an adhesive that's 10 times stronger than the force used by geckos to stick to surfaces and walk up walls.

The gecko's ability to stick is produced by myriad pillars located at the micro-nano scale on the underside of its foot, the researchers said. Because there are so many pillars so close together, they're held tightly to the surface the gecko is walking on by a molecular force called the Van der Waals force that causes uncharged molecules to attract each other.

In the new research, University of Dayton Professor Liming Dai and colleagues constructed their adhesive from two slightly different layers of multi-walled carbon nanotubes. The lower layer is composed of vertically aligned nanotubes, while the upper segment that contacts the surface it is sticking to is composed of curly nanotubes.

They said the adhesive works best when pulled down parallel to the surface it is sticking to in an action called shear adhesion. That arranges the tips of the curly nanotubes so they have maximum contact with the substrate, maximizing the Van der Waals force.

The complex research appears in the journal Science.